Incorrect Free Space / xfs_growfs on RAID5 Volume ?

[Svavar Örn Eysteinsson]

Hi.

I read on http://www.carltonbale.com/2007/05/how-to-break-the-2tb-2-terabyte-file-system-limit/
that if your kernel is compiled with CONFIG_LBD You can break the 2tb  
limit. Any facts on that ?

****
Breaking 2TB Option 2 - Use Linux with CONFIG_LBD enabled. Most Linux  
file systems are capable of partitions larger than 2 TB, as long as  
the Linux kernel itself is. (See this comparison of Linux file  
systems.) Most Linux distributions now have kernels compiled with  
CONFIG_LBD enabled (Ubuntu 6.10 does, for example.) As long as the  
kernel is configured/compiled properly, it is straight-forward to  
create a single 4TB EXT3 (or similar) partition.

     * To summarize: 1 RAID array of five 1TB Drives -> 1 RAID level 5  
Volume Set that is 4TB -> 1 EXT3 (or similar) Linux partition that is  
4TB.
****

.... Is this maby out of my scope/setup ?


Is there a simple way for me to check if my kernel has this option  
compiled in ?
I'm running Fedora Core 6 with  2.6.27.7 #1 SMP Tue Nov 25 11:50:10  
GMT 2008 i686 i686 i386 GNU/Linux.


And the FINAL question.... Is there any way for me to alter the raid  
volume, partitions to GPT or just format the /dev/sdb without loosing  
any data ?
Maby it's just not possible without backup up data, and restore'ing ?


Thanks allot guys..


Best regards,

Svavar - Reykjavik - Iceland



On 26.5.2009, at 12:46, Michael Weissenbacher wrote:

> Hi Svavar!
>> Now the strange part. When I issue “df -h” command it shows much  
>> smaller
>> disk space added then it should have.
>
> You have run into the 2TB limit for a DOS Paritition Table. You must  
> use GPT (GUID Partition Table) to overcome the limit. You can't use  
> fdisk for that since it has no GPT support. An alternative would be  
> parted [1]. I'm not sure how this can be done without data loss. An  
> alternative would be to not use partitions at all and create the XFS  
> directly on /dev/sdb.
> This is not really an XFS issue but an partitioning issue.
>
> [1] http://www.gnu.org/software/parted/index.shtml
>
> hth,
> Michael